Fluxing pipe



A ril 16, 1968 W. W. CARPENTER ET AL FLUXING PIPE Filed Sept. 16, 1965 4 0 yaw \v i +5 5 FiG-Z WOODROW W. CARPENTER ELMER SEIBERT United States Patent 3,378,037 FLUXING PIPE Woodrow W. Carpenter, Cincinnati, Ohio, and Elmer Seibert, Believue, Ky., assignors to Ceramic Coating Company, Newport, Ky., a corporation of Kentucky Filed Sept. 16, 1965, Ser. No. 487,780 4 Claims. (Cl. 138146) ABSTRACT OF THE DISCLOSURE A fiuxing pipe for delivering fluid to a mass of molten metal having a fired porcelain enamel applied to the interior and exterior of the pipe and an additional interior coating of glass fired to the interior coating of porcelain enamel. The pipe may be substantially closed at one end by means of an end cap or by being deformed and contains a plurality of side vents adjacent to the closure for lateral fluid delivery. The pipe may also be bent in an obtuse angle intermediate its ends.

This invention relates to an improved fiuxing pipe, and to an improved method of manufacturing the same.

It is well known in the art that when molten metals are to be purified or de-gassed, means must be provided for passing a purifying or de-gassing agent through the molten metal. This is commonly accomplished by inserting a pipe into the molten metal, and feeding through the pipe and into the melt, gaseous chlorine, nitrogen, oxygen or the like, under moderate pressure.

The pipe employed is commonly referred to as a fluxing pipe, and in use, such pipe is manipulated with a stirring motion so as to deliver and distribute the purifying or de-gassing agent throughout all portions of the melt. Depending upon the nature of the furnace in which the molten metal is treated, the fiuxing pipe may be either a straight pipe or a bent pipe, usually several feet in length.

Fuxing pipes generally are short-lived, due to the corrosive action of both the molten metal and the purifying or de-gassing agent to which the pipes are exposed. A black iron fiuxing pipe, for example, when used to feed chlorine into molten aluminum at 1380" F., will have a usefuii life of approximately ten minutes.

In order to prolong the life of the fiuxing pipes, some have been formed of iron or steel coated inside and outside with porecelain enamel. Others have been formed wholly or primarily of graphite. The graphite pipes, however, were quite expensive and subject to frequent breakage. The porcelain enameled iron pipe solved the breakage problem, but had inherent disabilities that limited its useful life to approximately two hours, which constitutes performance far short of economic and eflicient production goals.

Other solutions to the problem of short-lived fiuxing pipes have been proposed, including applying a tubular ceramic member or liner to the inside surface of a black iron pipe; also, applying tubular ceramic members to both the inside and the outside surfaces of such pipes. These methods were unsuccessful, due to the tendency of the ceramic members to crack and break under the strain of expansion differentials between the iron pipe and the ceramic members, occurring when the composite was lowered into the molten metal. Fluxing pipes so constructed were even less serviceable than the graphite pipe and the iron pipe treated with porcelain enamel.

One of the objects of the present invention is to produce a fiuxing pipe characterized by a greatly extended useful life span.

Another object of the invention is to provide an improved fiuxing pipe construction which is highly resistive ice to breakage, as well as the deteriorative effects of molten metal and treating agents therefor, so that efliciency of the device is materially enhanced, and the production of high-quality metals is facilitated and expedited.

Another object of the invention is to effect substantial savings of labor and other expense factors in the production of purified metals.

A further object is to provide an improved and efiicient method of producing fiuxing pipes of the character herein referred to.

Another object of the invention is to provide structural improvements in a fiuxing pipe, conductive to rapid and thorough de-gass-ing and purifying of molten metal, with increased efficiency and economy.

A further object is to provide a novel fiuxing pipe having a bend therein, produced according to a novel fabricating procedure of the present invention.

The foregoing and other objects are attained by the means described herein, and illustrated upon the accompanying drawing, in which:

FIG. 1 is a side elevational view of a straight fiuxing pipe, with broken lines suggesting a bend that might be incorporated in the pipe.

FIG. 2 is a side elevation showing a fiuxing pipe in modified form.

FIG. 3 is a similar view illustrating a further modification.

FIG. 4 is an end view taken on line 4-4 of FIG. 3.

FIG. 5 is an enlarged cross-sectional view taken on line 5'5 of FIG. 1.

FIG. 6 is a side elevational view of the fiuxing pipe, shown in the course of fabrication.

FIG. 7 is a side elevation, partly in cross-section, showing a pipe fitting that may be used in the course of fabrieating the fiuxing pipe.

FIG. 8 is a side elevation view of a fiuxing pipe with a bend in the pipe intermediate its ends.

In all of the drawing views, the fiuxing pipe indicated generally by the reference character 10, is constituted of a core tube 12 of metal, to which is applied at least one outer coating 14, at least one inner coating 16 of porcelain enamel, and a final inner liner 18 of glass fused to inner coating 16. The core tube 12 may be a commercial steel or black iron pipe having the usual resistance to bending, and which may, if desired, be externally threaded at one or both ends by means of ordinary pipe threading dies. Pipe threads are shown at 20 in FIGS. 1 and 6, and may be provided also at the capped end of the pipe illustrated by FIG. 2.

In the process of manufacture, the core tube 12 of ferrous metal is prepared for coating by sand blasting, pickling, or other known cleaning treatment. Then a porcelain enamel coating is applied to both the inside and the outside surfaces of the tube, using the commonly known techniques of the porcelain enameling industry. A second coating of porcelain enamel may or may not be applied, depending upon the nature of the service the fiuxing pipe is to perform, or the severity of service conditions to be encountered thereby.

After porcelain enameling, the core tube is provided with a glass lining 18. The glass lining may be applied by inserting into the porcelain enameled tube an elongate glass tube 22, FIG. 6, having an end portion 24 extended beyond the enameled tube. Upon firing, the extended end 24 softens, and by capillary attraction creeps onto the adjacent terminal end portion of the fiuxing pipe to cover and fuse with the previously applied porcelain enamel at the pipe end.

The glass liner tube 22 throughout its length is to be intimately fused to the inner coating of porcelain enamel, and this may be achieved by bringing the assembly to fusing temperature and pulling a vacuum between the glass tube and the enameled inner wall of the core tube. To properly apply the vacuum, the glass tube may be initially closed at one end 26, and the adjacent threaded end 20 of the enameled tube may be equipped temporarily with an internally threaded pipe fitting 28 having a nipple 30 for connection with a vacuum generator pipe, not shown. As the glass tube and the surrounding pipe reach fusing temperature, the vacuum pulls the plastic closed end 26 into the fitting 28, and forces the glass tube into intimate contact with the entire inner surface of the porcelainized core tube. Fusion under these conditions ensures formation of a continuous glass liner Within the fluxing pipe, which covers any pin-holes that might have existed in the porcelain enamel coating.

The elimination of pin-holes is very important to the life of the finished fluxing pipe, and such is a primary function of the glass liner. In place of the vacuum process above recited, a pressure method may be employed for pressing the glass tube against the inside pipe wall during fusion. Such method may involve pumping air or other gas into the glass tube while oppositeends of the glass tube are scaled closed. As an alternative, the glass tube in sealed condition may encase a chemical, such as potassium perchlorate, which under high temperature conditions emits a gas and produces pressure Within the tube to press same into intimate contact with the inner wall of the porcelainized core tube during fusion.

It should here be noted that theg ass tube may be inserted into the core tube, and fused therein, either concurrently with or subsequently to fusion of the porcelain enamel frit to the core tube.

By the method above described, the fluxing pipe may be produced as a straight pipe, FIG. 1, either with or without vents such as 32. If a bent fluxing pipe is desired, 7

as suggested by broken lines 34, the fired and finished straight pipe may be reheated to a temperature between 1300 F. and 1500 F., and then bent by hand method or mechanical means while it is still red hot. The reheating must be performed in a furnace in which the atmosphere contains no more than about 4.3% moisture. If a greater amount of moisture is present in the furnace atmosphere, the porcelain enamel coatings will blister and pin-hole, thus producing defects which render the fluxing pipe practically useless. FIG. 8 illustrates a fluxing pipe 10 bent in an obtuse angle as indicated at 42 and terminates in end portion 34'.

A further observance for preventing porcelain enamel defects in the fluxing pipe, is the proper selection of chemical composition of the iron used to make the core tube or pipe. The chemical composition should fall within the following limits:

Percent Carbon 002.10 Manganese .04-.38 Phosphorus DOS-.015 Sulphur .025.038

Slightly higher percentages of the foregoing elements can be tolerated, but will necessitate a carefully controlled rate of heating prior to bending of the fluxing pipe.

The bending procedure above recited is applicable to porcelain enamel covered iron pipe produced either with or without the glass tube insert.

In the production of fluxing pipes for use in degassing or purifying molten aluminum, the iron core tube may desirably be provided with two coatings of porcelain enamel, particularly on the exterior surface thereof. The second coating will preferably contain a sufliciently high percentage of aluminum oxide, zirconium oxide, magnesium oxide, or silicon. dioxide, to resist the wetting action of the molten aluminum. Also, the second coating may be formulated to compensate for expansion diiferem tials between the iron core tube and the inserted glass 4 tube 22, to preclude cracking and breaking of the coating material.

The coeflicient of expansion of the innermost porcelain coating may readily be adjusted to a Value between that of the iron tube, and that of the glass tube, by altering the percentages of sodium oxide and boron oxide within the frit used to formulate the porcelain enamel coating. The assembly including the glass tube 22 should be heated to a temperature of 1400 F. to 1600" F., in order to fuse the glass to the above mentioned inner coating of porcelain enamel. As before explained, the glass tube will be fused into place while forced against the inner wall of the iron core tube by positive or negative pressure.

In addition to the foregoing improvements is that improvement which involves the formation of a vented tip at the delivery end of the fluxing pipe. Such vented tips are indicated at the right ends of FIGS. 1, 2, and 3, and also by FIG. 4. Such tips have proven highly effective for expediting and facilitating de-gassing, by releasing the de-gassing and purifying agent under pressure in many directions from the tip, as the fluxing pipe stirs the melt. When the fluxing pipe is side-vented as shown at 32, its adjacent terminal end should be sealed closed, or substantially constricted, to enforce delivery of the de-gassing agent through the side vents or ports.

To side-vent the device, the iron core tube 12 prior to coating with porcelain enamel, is drilled or punched to form a number of holes in the side Wall thereof, near the terminal end 34. The holes as drilled or punched should be considerably oversized, since in the finished product such holes will be constriced in size by porcelain enamel and glass fused to the tube inside and outside as previously explained. The holes initially may be formed in the iron core tube with a diametral dimension of .25 7

inch, more or less.

During fusion of the porcelain enamel, and of the glass insert 22, the holes 32 (FIG. 5) will fill up to some extent with glass and porcelain, to form a thin web '36 across each hole. After cooling, the thin webs 36 can be punctured using an ordinary hand punch or the like, to form small holes suitable for delivery of a de-gassing agent. The punching-out of web 36 does not clear the hole 32 of glass or porcelain, but instead, leaves a liberal cover enveloping completely all edges of the hole initially formed in the iron core tube as indicated by the numeral 20. In this way, the edges of all the holes or side vents are adequately protected against the ravages of the molten metal and the de-gassing agents to which the fluxing pipe will be exposed in use.

When the fluxing pipe is side-vented, its terminal end at the vents should either be closed or constricted, to enforce delivery of the de-gassing agent radially of the pipe. For example, according to FIG. 2, the terminal end of the fluxing pipe is closed by means of an iron or steel pipe cap 38 threadedly applied thereto. The cap is coated with porcelain enamel and fused to protect it against rapid destruction, and if any threads at the threaded connection are exposed, these will be thoroughly protectively covered with a silicate type cement such as is available commercially.

struction, wherein the terminal end near the side vents may be constricted, rather than closed. Here, the vented end had been reheated to a temperature of 1300" F. to 1500 F., and while red hot, was mashed laterally by means of a hammer and anvil, or other suitable expedient, to distort the pipe as at 40. The distortion might be only limited, as shown, to restrict flow of gas through the end of the pipe, or if desired, a more thorough distortion may be resorted to for completely blocking flow of gas through the end of the pipe. In either case, there is provided an opportunity for delivery of degassing material through the side vents 32. The mutilation at 40 is effected preferably after all protective coatings have been fused to the pipe.

The pipe closing depicted at 40 can be eflected upon the ends of fiuxing pipes which are porcelain enameled, with or Without the glass insert incorporated therein. The pipe end, of course, may be either straight or bent as suggested by FIG. 1. If the pipe of FIG. 1 is to be side vented by means of apertures 32, the terminal end 34 of the pipe should preferably be closed, using either the FIG. 2 or the FIG. 3 method, or some other effective method. If the pipe is not to be side vented, its terminal end 34 will be open for delivery of the de-gassing agent.

It is to be understood that various modifications and changes may be made in the method disclosed, and in the structural details of the device produced by said method, all within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed is:

1. A fiuxing pipe for delivering fluid to a mass of molten metal, comprising: an elongate tube of ferrous metal having opposite ends, interior and exterior coatings of fused porcelain enamel applied to the tube, and an additional interior coating of glass fused to the interior coating of porcelain enamel, said coatings forming protective liners within the tube.

2. The device according to claim 1, wherein the pipe is bent at an obtuse angle intermediate its ends.

3. A fluxing pipe as set forth in claim 1 wherein one of the ends of said elongated tube is substantially closed and contains a plurality of side vents in the tube adjacent to said substantially closed end for lateral fluid delivery.

4. A fluxing pipe as set forth in claim 1 wherein one of said ends of the elongated tube is closed by means of a cap and contains a plurality of side vents in the tube adjacent to the end cap for lateral fluid delivery.

References Cited UNITED STATES PATENTS 1,124,281 1/1915 Bradley 117-70 X 1,944,733 1/1934 Doerichikt 117-97 X 2,391,468 12/1945 Long 138-145 X 2,606,574 8/1952 Iefebvre 138-140 X 2,774,384 12/1956 Wallace 138-1'40 X 2,897,096 7/1959 Karatxas et a1. 117-70 2,986,847 6/1961 Sato 138-141 3,036,929 5/1962 Kawashirna et a1. 138-146 X 3,044,499 7/1962 Frerich 138-143 3,062,685 11/1962 Sanford et al 117-70 X 3,129,727 4/1964 Tanaka 138-143 3,132,979 5/1964 Bickerdike et a1. 138-141 X 3,141,479 7/1964 Mickey 138-143 3,143,147 8/1964 Sellars et a1. 138-140 3,269,423 8/1966 Goto 138-140 3,290,137 12/1966 Tisinai 138-141 X 3,292,662 12/1966 Nishi 138-141 3,303,041 2/1967 Thompson 117-97 X 3,314,450 4/1967 Doering et a1. 138-146 LAVERNE D. GEIGER, Primary Examiner.

H. S. BELL, Assistant Examiner. 

